Rabejacite, Ca(UO (sub 2) ) (sub 4) (SO (sub 4) ) (sub 2) (OH) (sub 6) .6H (sub 2) O, a new uranyl and calcium sulfate from Lodeve, Herault, France

Rabejacite occurs as flattened tablets, acicular crystals or rounded nodules (< or = 0.3 mm) associated with gypsum in the oxidation zone of U ores in red pelites from Rabejac, 7 km S-SE of Lodeve, and in grey Autunian rocks from Mas d'Alary Village, 3 km S-SE of Lodeve. It is bright to amber yellow, transparent to translucent with a vitreous lustre; alpha 1.617, beta 1.710, gamma 1.758, 2V (sub alpha) 68 degrees ; pleochroism beta pale yellow, gamma sulphur yellow; orientation alpha = c, beta and gamma in the plane of the tablets; D > or = 4.10 g/cm (super 3) . Indexed XRD powder data are tabulated; strongest lines 7.90(100), 3.49(80), 3.38(70), 3.98(40), 4.17(30) Angstrom ; a 8.73, b 17.09, c 15.72 Angstrom ; Z = 4. The average of 20 EPMA results gave CaO 2.78, UO (sub 3) 76.62, SO (sub 3) 10.43, with H (sub 2) O 10.18, [= 100.01], leading to the formula Ca(UO (sub 2) ) (sub 4) (SO (sub 4) ) (sub 2) (OH) (sub 6) bullet 6H (sub 2) O.